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' tionsgiven, as they 'may be slightly varied without SAMUEL LENHER AND HALLAM H. SPENCER, OF PHILADELPHIA, PENN- SYLVANIA.

Letters Patent No. 97,528, (la-ted December 7, 1869.

, IMPROVED MODE OI PREPARING PAPER FOR PRINTING POSTAGE AND REVENUE-- STAMPS.

The Schedule referred to in these Letters Patent and making part of the same.

i To all whom it may concern:

Be it known that we, SAMUEL LENHER and Hat;- LAM H. SPENOER,1)Ot-h 0t the city and. county of Philadelphia, and State of Pennsylvania, have invented a certain new and useful Improvement in Pre paring .Paper for Printing Revenue and Postage- Stamps; and we do hereby declare that the following is a full, clear,'and exact description thereof, which will enable others skilled in. the art to which it appertains, to make and use our invention;

The object of our said invention is to prevent the restoration of cancelled stamps. This we accomplish by coating the paper, previously tov printing, with a sizing, of which the essential ingredients are an earthy substance, which is insoluble in water, and easily decomposed by acids, and 'a glutinous substance, which We compound this preparation or one pound of carbonate of line, carbonate of baryta, carbonate of magnesia, or other earth which is insoluble in water, and easily decomposed by acids, carbonic-acid gas being readily eliminated, to which earthy body, we add an ounce and a half of glue, two ounces ofgum-arabic, dextrine, or other gum, which is readily soluble in water, and one quart of water. H

We do not confine ourselves to the precise proporsubstantially afl'ecting the nature of the composition; but westate those proportions which we have found to be most advantageous in practice. We would also state that the gumming-ingredient may be dispensed with, as it is not essential either to the adhesivencs's of the size, nor to itsready disintegration, but we pre fer to use it, as itrenders the sizing more soluble.

To compound the ingredients above named, we dissolve the glue or gum and glue in the water, which we beat until either or both are dissolved, and then stir in the earthy body ti l it is thoroughly mixed.

When the mixture is perfectly smooth and of uniform consistency, we apply it to the paper in any convenient way, laying it on with .a brush, or by means of the machinery commonly employed for coating wallpaper. When the paper thus prepared has been slightly dampened, it is ready for printing.

The stamp having been cancelled, whether with printers ink, writing-fluid, or any other ink, should it be attempted to obliterate the mark of cancellation by means of an acid, the chemical action of theacid on the earthy body, eliminating the carbonic-acid gas, will decompose the size, and consequently eflace the print,

If the attempt be made with other substances, such as water or ulkalics, the glutinous and gummy ingredients will be dissolved, not only by chemical action, but also by the mechanical action necessary to efl'ace the mark, so that, in any event, the mark of cancellation cannot be removed without disintegrating the sizeand theyeby defacing-the print.

We do not claim printing a stamp on sizing inter posed between the printing-ink and the paper, as we are aware that that is a well-known process; but

\Vhat we do claim as our invention, and desire to secure by Letters Patent of the United States, is-

1. The preparation, compounded of the ingredients specified, and for the purpose set forth.

2. vAprepaiation for printing postage or revenuestamps upon, and from which the mark of cancellation cannot'bc eii'aced, without disintegrating such preparation, either by chemical action alone, or by chemical and mechanical action combined, substantially in the manner described.

SAMUEL LENHEL. H. HJSPENOER.

Witnesses GEORGE E. BUUKLEY, WILLIAM J. BURNS. 

